Methods and apparatus for distal protection during a medical procedure

ABSTRACT

Apparatus and methods for providing distal protection during a medical procedure comprising a vascular filter having a self-expanding, porous foam body that conformably seals against a vessel wall and captures emboli within one or more recesses. The filter is coupled to a distal region of an elongated member, such as a guide wire. Delivery systems for use with filters of the present invention and methods of using the apparatus of the present invention also are provided.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for filteringmaterial from a body lumen. More particularly, the present inventionprovides a resiliently self-expanding foam filter adapted to capture andremove emboli, thrombus, and foreign bodies from a patient'svasculature.

BACKGROUND OF THE INVENTION

Percutaneous interventional procedures to treat occlusive vasculardisease, such as angioplasty, atherectomy and stenting, often dislodgematerial from the vessel walls. This dislodged material, known asemboli, enters the bloodstream, and may be large enough to occludesmaller downstream vessels, potentially blocking blood flow to tissue.If the blockage occurs in critical tissue, such as the heart, lungs, orbrain, resulting ischemia poses a serious threat to the health or lifeof a patient.

Additionally, the deployment of stents and stent-grafts to treataneurysms, ruptures, and other vascular diseases may result in theformation of clots or emboli. Such particulate matter also may causeinfarction or stroke if released into the bloodstream. Furthermore,interventional procedures may generate foreign bodies that are leftwithin a patient's bloodstream, thereby endangering the life of thepatient. Foreign bodies may include, for example, a broken guide wire,pieces of a stent, or pieces of a catheter.

Numerous previously known methods and apparatus have been proposed toreduce complications associated with embolism, thrombus release, orforeign body material generation. U.S. Pat. No. 5,814,064 to Daniel etal. describes an emboli filter system having a radially expandable meshfilter disposed on the distal end of a guide wire. The filter isdeployed distal to a region of stenosis, and any interventional devices,such as angioplasty balloons or stent delivery systems, are advancedalong the guide wire. The filter is designed to capture emboli generatedduring treatment of the stenosis while permitting blood to flow throughthe filter. Similar filter systems are described in U.S. Pat. No.4,723,549 to Wholey et al. and U.S. Pat. No. 5,827,324 to Cassell et al.

One disadvantage common to many prior art radially expandable filtersystems, such as those described in the foregoing patents, is the numberof parts necessary to fabricate the devices. Connecting more than aminimal number of such parts to a guide wire generally increasesdelivery complications. The ability of the guide wire to negotiatetortuous anatomy is reduced, and the profile of the device in itsdelivery configuration increases. Consequently, it may be difficult orimpossible to use such devices in small diameter vessels, such as arecommonly found in the carotid and coronary arteries, as well as incerebral vasculature. Moreover, such filter devices are often incapableof preventing material from escaping from the filter during the processof collapsing the filter for removal.

Thus, there has been a long-felt need in the art for a simple, safe, andeffective emboli filter that does not significantly impede antegradeblood flow, that reduces stress applied to the vessel wall, thatconforms to the size and internal profile of the vessel in vivo toreduce escape of emboli past the filter, that may be collapsed forretrieval without loss of captured emboli, that may be sized for use insmall vasculature, and that may be used in tortuous anatomy withoutincreased delivery complications.

Foams are used in a variety of vascular medical applications. Forexample, U.S. Pat. No. 5,725,568 to Hastings describes the use ofbiocompatible foam as an occlusive agent during aneurysm repair. U.S.Pat. No. 5,837,140 to Fini et al. describes a blood filter fabricatedfrom polyurethane foam. The filter is contained within a semirigidhousing and is configured for use as part of an extracorporeal bloodcircuit. It is not suited for intravascular use.

U.S. Pat. Nos. 5,192,290 and 5,411,509 to Hilal, as well as U.S. Pat.No. 5,827,304 to Hart, describe embolectomy catheters having a portioncomprising an expandable elastomeric foam that may be used to removeblood clots from a patient's vessel. These foam portions aresubstantially spherical and presumably occlude or impede antegrade flowthrough the vessel; they are therefore not suited for use as embolifilters.

U.S. Pat. No. 6,152,947 to Ambrisco et al. describes an embolic filterhaving a plastic or metal frame attached to a filter mesh. Foam sealsmay be attached to the frame so that the frame conforms to and sealinglyengages the patient's vasculature. While foam seals may reduce embolileakage around an embolic filter and may be less traumatic to vascularintima, as compared to other previously known filters, foam seals are anadditional component that is expected to increase delivery profile andincrease delivery complications. That patent states at column 3, lines15-16, that the filter frame itself “may be metal, plastic, gel or foamor any combination thereof,” but provides no teaching as to how a filterframe fabricated exclusively from foam could be made or would function.Furthermore, Ambrisco does not describe a filter mesh fabricated fromfoam.

U.S. Pat. No. 6,010,531 to Donlon et al. describes a catcher adapted forplacement in a patient's left ventricle during aortic valve replacementsurgery to catch any debris released during leaflet removal, or in thedebridement process. The catcher comprises a flexible, porous mesh,foam, gauze, or screen constructed as a bag or pouch with an opening onthe top end. A flexible and resilient metal or elastomeric ring may bemounted to the catcher around the opening to allow the ring to collapsefor delivery and to expand to engage the ventricular wall. The catcheris attached to a tether, such as a suture, to facilitate positioningwithin the ventricle.

Donlon's catcher device has several drawbacks that make it unsuitablefor use as a vascular filter. The catcher is not disposed about a guidewire. It is not sized for use in small vasculature, and the metal orelastomeric ring mounted to the catcher would presumably kink if sizedfor such use. Furthermore, the metal ring would apply a potentiallytraumatic stress against the vessel wall.

U.S. Pat. No. 5,941,869 to Patterson et al. describes an embolic filterhaving a plurality of structural members that enclose and support anonthrombogenic expandable filter medium. The structural members aremade of metal or a polymer, and the expandable filter medium may be aporous foam material. As with previous filter devices, it is expectedthat the substantially rigid structural members will apply a stress tothe vessel wall that may damage or traumatize the wall.

U.S. Pat. No. 6,165,200 to Tsugita et al. describes a filter assemblyhaving a plurality of substantially cylindrical, expandable sponge-likeelements that are adapted to engage the wall of a patient's vessel. Thesponge-like elements are affixed to a guide wire and have sufficientporosity to allow blood, but not large emboli, to pass freelytherethrough. Additionally, the sponge-like elements may have varyingporosity that decreases along the length of the guide wire, so thatembolic material enters a proximal portion of the elements, but iscaptured within a distal portion of the elements. The patent claims thatvarying porosity along the length of the guide wire substantiallydecreases a likelihood that embolic material will be caught only on anouter surface of the sponge-like elements, thus reducing the risk thatemboli will be released when the sponge-like elements are retrievedwithin a sheath.

While it is expected that the filter assembly of the Tsugita patent willsealingly conform to the patient's vessel with reduced trauma or injury,the assembly has several drawbacks. Applicants disagree with theassertion in the Tsugita patent that varying porosity will substantiallyreduce the risk of emboli being liberated during retrieval. Red bloodcells have an approximate diameter of 5 microns. Dangerous emboli,meanwhile, are commonly defined as particles greater than about 60-100microns in diameter. Dangerous emboli, however, can vary in size as muchas an order of magnitude. Thus, unless a very substantial variance inporosity is provided (a variance not feasible for sponge-like elementssuitable used in small vasculature), it is expected that the largest andpotentially most dangerous emboli may not, or may only partially, enterwithin the pores rather than be caught against an outer surface of thesponge-like elements. During retrieval, some or a portion or all ofthese larger particles may escape into the blood stream.

Providing a plurality of sponge-like devices as in the Tsugita patent isexpected to have a number of drawbacks. First, a longer length of vesselis required to deploy the multiple sponge-like elements. Second, anincreased risk of complications, e.g. snagging or frictional sticking,exists while collapsing the long length of sponge-like elements back tothe delivery configuration. Third, the plurality of sponge-like elementsreduces trackability through tortuous anatomy. Fourth, the length of thesponge-like elements, coupled with their density, is expected to reducethe pressure of blood passing through the elements, thus potentiallycausing ischemia or damage to downstream tissue. The density and lengthof the sponge-like elements also may require a volume of material tofabricate the cylinders that renders disposal of the elements within adelivery sheath having a delivery profile suited for small vasculature,for example, a delivery profile as small as 3 Fr, unfeasible.

An additional drawback of the sponge-like elements is that, even ifdangerous emboli are captured within the pores, the emboli may besqueezed out of the pores during collapse of the elements back to thedelivery configuration. This risk is especially acute due to thedeployed, cylindrical profile of the sponge-like elements. The profileprovides a sharp step, or discontinuity, to a retrieval sheath that isexpected to increase retrieval complications.

In view of the foregoing disadvantages of previously known apparatus andmethods, it would be desirable to provide a vascular filter thatovercomes such disadvantages and employs few components.

It would be desirable to provide a vascular filter that conforms, andreduces a risk of trauma, to the vessel wall.

It also would be desirable to provide a vascular filter that is capableof being contracted to a small delivery profile, thus permitting use ofthe filter in small vessels.

It still further would be desirable to provide a vascular filter thatreduces a risk of emboli or thrombus removed from the vessel wallescaping from the filter when the filter is collapsed and removed.

It would be desirable to provide a vascular filter that does notsignificantly impede antegrade blood flow.

It would be desirable to provide a vascular filter having a filterelement fabricated solely from foam.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide a vascular filter that overcomes disadvantages of previouslyknown vascular filters and foreign body removal devices, and employs fewcomponents.

It is an object of the present invention to provide a vascular filterthat conforms, and reduces a risk of trauma, to the vessel wall.

It also is an object of this invention to provide a vascular filter thatis capable of being contracted to a small delivery profile, thuspermitting use of the device in small vessels.

It is another object to provide a vascular filter that reduces a risk ofemboli or thrombus removed from the vessel wall escaping from the filterwhen the device is collapsed and removed.

It is yet another object to provide a vascular filter that does notsignificantly impede antegrade blood flow.

It is an object to provide a vascular filter having a filter elementfabricated solely from foam. These and other objects of the presentinvention are accomplished by providing a vascular filter fabricatedfrom foam that is suited for both conformably sealing against a vesselwall and for capturing emboli within one or more recesses. The foam ispreferably porous with a pore size that allows blood, but notdangerously-sized emboli, to pass therethrough.

Porosity of the foam may be specified to control a pressure drop acrossthe vascular filter. The foam also is elastomeric, allowing the filterto self-expand from a collapsed delivery configuration to an expandeddeployed configuration. The foam filter is attached to a distal regionof an elongated member, such as a guide wire.

Advantageously, use of foam permits vascular filters constructed inaccordance with the present invention to be contracted to very smalldiameters for delivery without a delivery catheter, or with deliverycatheters having diameters as small as 3 Fr. Delivery catheters thatpermit a lesion to be crossed with an unencumbered guide wire prior topassage of the foam filter may be provided. Such catheters may beconfigured for “rapid exchange” use. When delivered without a deliverycatheter, filters of the present invention may be maintained in thedelivery configuration by, for example, a removable suture that isremoved once the filter is properly positioned within the patient'svessel. During deployment, an occlusion device, such as a standardballoon catheter, may be employed to arrest antegrade flow through thevessel, and thereby antegrade advancement of emboli, until the vascularfilter is deployed.

Vascular filters of the present invention may be collapsed for retrievalwithin the guide wire lumens of conventional treatment devices, such asangioplasty catheters and stent delivery systems, thereby obviating theneed to re-insert a specialized retrieval catheter to remove thevascular device. However, a retrieval sheath having a distal region thatflares or expands outwardly to receive the emboli-filled recesses of thefilter upon completion of an interventional procedure, may optionally beused in accordance with the present invention.

Methods of using embodiments of the present invention are also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention, its nature and various advantageswill be more apparent from the following detailed description of thepreferred embodiments, taken in conjunction with the accompanyingdrawings, in which like reference numerals refer to like partsthroughout, and in which:

FIGS. 1A-1C are, respectively, a perspective view of a vascular filterconstructed in accordance with the principles of the present inventionin a deployed state, a cross-sectional view of the filter along sectionline A-A in FIG. 1A, and a side-sectional view of the filter alongsection line B-B in FIG. 1B;

FIGS. 2A-2C are side-sectional views of alternative embodiments of thevascular filter of FIG. 1;

FIG. 3 is a side view of a delivery system for use with vascular filtersof the present invention;

FIG. 4 is a side view, partially in section, of an alternativeembodiment of the delivery system of FIG. 3; and

FIGS. 5A-5E are side sectional views depicting a method of deploying,using, and retrieving the vascular filter of FIG. 1 using the deliverysystem of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to methods and apparatus for filteringmaterial from a body lumen. More particularly, the present inventionprovides a resiliently self-expanding foam filter adapted to capture andremove emboli, thrombus, and foreign bodies from a patient'svasculature.

With reference to FIG. 1, a first embodiment of apparatus in accordancewith the present invention is described. Filter 10 comprises foam body12 defining at least one bore or recess 14. In FIG. 1, foam body 12 isillustratively depicted with three recesses 14 separated by partitions16, but any number of recesses may be provided, as will be apparent tothose of skill in the art. Foam body 12 is coupled to a distal region ofelongated member 18, which is preferably radiopaque. Filter 10 may alsooptionally comprise one or more radiopaque features (not shown) thatfacilitate positioning of the filter within a patient's vasculature.Elongated member 18 preferably comprises a standard guide wire.

Foam body 12 is fabricated from foam that is suited for both conformablysealing against a vessel wall and for capturing emboli within recesses14. The foam is preferably open-celled having pores with a pore sizethat allows blood, but not dangerously sized emboli, to passtherethrough. Alternatively, the foam may be closed-celled, in whichcase pores may be manually formed, for example, by laser drilling. Thepores preferably have a minimum diameter greater than approximately 5μm, and a maximum diameter smaller than approximately 100 μm. Morepreferably, the pores have a diameter in a range of between about 60 and80 μm.

In the context of this written description, the pores need not bespherical, but may be of any irregular shape. Accordingly, in thiswritten description, a reference to the “diameter” of a pore refers tothe average width of an external opening or the pore or an averagediameter of an irregularly shaped void.

Porosity, i.e. the density of pores, within the foam may be specified tocontrol a pressure drop across the vascular filter when used within apatient's vasculature. The foam is also preferably resilient orelastomeric, allowing the filter to self-expand from a collapseddelivery configuration to an expanded deployed configuration. Suitablefoams may comprise, for example, foams fabricated from latex, silicone,or polymers, such as polyethylene, polyurethane, polycarbonate,polyvinyl chloride, polystyrene, polypropylene, and polyester.

Foam body 12 is preferably tubular, with partitions 16 that extend in atapering fashion beyond proximal end 20 of recesses 14. The tubularshape of body 12 provides for contact of a substantial length of filter10 against the interior of a patient's vessel, as compared topreviously-known filter hoops, struts, etc. This substantial contactlength is expected to distribute forces that are applied by the filterto the patient's vessel over a greater area, thereby reducing stress anda potential for injury to the vessel wall. The substantial length alsoprovides a good seal against the vessel wall.

Additionally, during retrieval and/or repositioning of filter 10, thecontact length of filter 10 acts as a linear bearing and is expected toreduce a risk of ‘stiction’, or torqued sticking, against the vesselwall that may occur if the wall is contacted over an insufficient lineardistance. Stiction may make it difficult or impossible to remove anembolic filter without performing emergency cut-down surgery. To reducestiction, the length of a filter between its proximal and distal pointsof contact with the vessel wall is preferably greater than or equal toabout 1½ times the internal diameter of the vessel, and is even morepreferably greater than about 2 times the internal diameter.Accordingly, for filter 10, the distance between proximal end 20 ofrecesses 14 and distal end 22 of the filter is preferably greater thanabout 1½ times, and even more preferably about 2 times, a maximum widthof foam body 12.

As best seen in FIGS. 1B and 1C, recesses 14 extend within a substantialportion of foam body 12, thereby significantly reducing the solid volumeof foam body 12 and facilitating contraction of filter 10 to a collapseddelivery configuration suited for intravascular delivery within smallvasculature, for example, a delivery configuration of less than about 3Fr. Additionally, the size and configuration of recesses 14 allow foreffective capture of emboli, foreign bodies, and thrombus both large andsmall, while still allowing continued blood flow through distal end 22of the filter.

As seen in FIGS. 1A and 1C, partitions 16 preferably taper proximally ofrecesses 14 to a point of union 17 having a cross-section that is justslightly larger than the diameter of elongated member 18. Elongatedmember 18 is coupled to foam body 12 of filter 10 along the line ofunion of partitions 16 extending distally from point of union 17. Thetapering of partitions 16 provides a smooth, substantially continuoustransition between the diameter of the elongated member and the maximumwidth of filter 10 that is expected to facilitate capture of filter 10within a retrieval catheter with reduced force application.Additionally, the transition facilitates closure of proximal end 20 ofrecesses 14 prior to capture of recesses 14, thereby trapping emboliwithin the recesses and preventing escape of emboli during retrieval.Optionally, filter 10 also may be coated with a non-stick coating C thatreduces friction during deployment and retrieval of the filter. CoatingC may comprise, for example, a silicone or polytetrafluoroethylenecoating.

Filter 10 may be manufactured using a variety of techniques. Forexample, a cylindrical section of open-celled foam of proper diametermay be cut to the length of filter 10, thereby forming a cylindricalplug. Closed-celled foam may alternatively be used, in which case poresmay be manually formed within the foam, for example, by laser drilling.

Once a cylindrical plug has been cut, recesses may be bored into theplug from its proximal end to a position just proximal of its distalend. Side cuts are then made in the proximal region of the plug to formfilter 10 with recesses 14 and tapering partitions 16. Finally,elongated member 18 is attached to the filter by drilling a small holealong the line of union of partitions 16. Elongated member 18 then isadvanced through the drilled hole until filter 10 is disposed about thedistal region of the elongated member. The elongated member is affixedto the filter, for example, with an epoxy or with a friction fit.Boring, cutting, and drilling operations may be achieved using standardequipment, per se known, or with a laser.

Referring now to FIG. 2, alternative embodiments of vascular filter 10are described. In FIG. 2A, foam filter 40 is substantially equivalent tofilter 10, except that elongated member 42 comprises proximal section 44and distal section 46 that are gapped, or spaced apart from one another.Proximal section 44 is attached to filter 40 along the filter's proximalregion, while distal section 46 is attached along the filter's distalregion. Since elongated member 42 is not attached to, nor disposedwithin, a central region of filter 40, it is expected that filter 40 maybe collapsed to an even smaller delivery profile than filter 10 of FIG.1.

In FIG. 2B, filter 50 comprises lumen 52 that extends along the line ofunion of partitions 16. Elongated member 18 is disposed within lumen 52and is provided with proximal and distal stops 19 a and 19 b,respectively, such as described in U.S. Pat. No. 6,179,859. Filter 10 isthus longitudinally restrained with respect to member 18; however, itmay rotate independently of the elongated member. This is expected tofacilitate advancement of filter 50 to a target site, as well asexpansion, use, and retrieval of the filter, by allowing independenttorqueing of elongated member 18. Stops 19 are preferably radiopaque tofacilitate positioning of filter 10. Alternatively, as described in theaforementioned patent, elongated member 18 may include only a distalstop 19 b, thereby allowing filter 10 to be advanced along elongatedmember 18 after the elongated member is placed in a vessel.

In FIG. 2C, filter 60 comprises solitary recess 62, and partitions 64 donot extend within the tubular portion of filter 60. Instead, thepartitions only extend, and taper, from proximal end 66 of recess 62 toproximal point of union 68 of partitions 64. At point of union 68,partitions 64 have a cross-section that is just slightly larger than thediameter of elongated member 18. Thus, as with partitions 16 of filter10, partitions 64 provide filter 60 with the smooth, substantiallycontinuous transition between the diameter of the elongated member andthe maximum width of filter 60 that facilitates capture of filter 60with reduced force application, as well as closure at proximal end 66 ofrecess 62. However, since partitions 64 do not extend within the tubularportion of filter 60, it is expected that filter 60 may be collapsed toan even smaller delivery profile than filter 10. As will be apparent tothose of skill in the art, within the tubular portion of filter 60,partitions 64 alternatively may extend just along their line of union(not shown), thereby reducing the volume of filter 60, while stillproviding attachment of elongated member 18 along the entire length offilter 60.

With reference now to FIGS. 3 and 4, alternative delivery systems forfilters of the present invention are described. The delivery systems areillustratively depicted in use with filter 10, but obviously filters 40,50, or 60, or any other filter in accordance with the present invention,could be substituted for filter 10.

In FIG. 3, delivery system 70 comprises tear-away suture 72 that iswrapped about filter 10 to dispose the filter in a collapsed deliveryconfiguration. Filter 10 is coupled to elongated member 74, whichcomprises lumen 76 that extends from proximal end 78 to through-hole 80.Suture 72 extends through lumen 76, out of through-hole 80, and aroundfilter 10, and is then attached to elongated member 74 distal of filter10. When filter 10 is positioned at a treatment site, a physician maypull on the proximal end of suture 72 to cut or tear away the suture,thereby releasing filter 10, which self-expands to its original,non-compressed, deployed configuration. Through-hole 80 of elongatedmember 74 may, for example, be sharp to facilitate cutting of thesuture. Other techniques for releasing the suture will be apparent tothose of skill in the art. Advantageously, delivery system 70 eliminatesthe need for an external sheath to deliver filter 10, thereby reducingthe delivery profile of the system and allowing filter 10 to bedelivered on a “bare” guide wire.

Referring to FIG. 4, an alternative delivery system for filters of thepresent invention is described. Delivery system 90 comprises deliverysheath 92 having lumen 94 extending therethrough. Sheath 92 may comprisea full-length sheath, as seen in FIG. 4, or may alternatively comprise ashorter sheath (not shown) sufficient for disposal of filter 10 therein.Sheath 92 preferably comprises radiopaque marker 96 along its distalregion 98 that facilitates positioning of delivery system 90 at atreatment site. Alternatively or in addition to marker 96, sheath 92 maycomprise a radiopaque marker disposed proximally of filter 10 (notshown) that facilitates, for example, easy determination of when thefilter has been advanced past a stenosis.

Filter 10 is disposed in a delivery configuration within distal region98 of sheath 92. This may be accomplished, for example, by advancingdistal region 98 over the proximal end of elongated member 18 untilproximal point of union 17 of partitions 16 of filter 10 abuts thedistal end of sheath 92. Continued advancement of sheath 92 with respectto filter 10 causes the sheath to contact the tapered section ofpartitions 16, thereby gradually collapsing filter 10 to its deliveryconfiguration and closing recesses 14.

A similar technique may be used to collapse filter 10 within a retrievalsheath after capture of emboli, thrombus, etc., within recesses 14.Optional coating C on the surface of filter 10 may facilitate loading ofthe filter within sheath 92, as well as deployment of the filter, byreducing friction between the sheath and the filter. Filter 10 may bedeployed within a body lumen by retracting sheath 92 with respect tofilter 10 so that filter 10 resiliently expands to the deployedconfiguration of FIG. 1. Alternatively, filter 10 may be deployed byadvancing the filter with respect to sheath 92.

Optionally, delivery sheath 92 may be provided with an additional guidewire lumen (not shown) that permits a lesion to be crossed with anunencumbered guide wire prior to passage of filter 10. This is expectedto reduce emboli generation during placement of filter 10. Theadditional guide wire lumen may be configured for “rapid exchange” use,and/or may simply comprise a hypotube attached to the exterior of sheath92 along distal region 98.

During deployment of filter 10, an occlusion device (not shown), such asa standard balloon catheter, may be used in conjunction with, or as partof, the filter's delivery system. Such an occlusion device may be usedwith delivery systems 70 and 90, or with other delivery systems thatwill be apparent to those of skill in the art. The occlusion device mayarrest antegrade flow through a vessel, thereby arresting antegradeadvancement of emboli until filter 10 has been deployed to capture theemboli.

Referring now to FIG. 5, a method of using apparatus of the presentinvention is described. FIG. 5 are illustratively depicted with filter10 and delivery system 90. However, alternative filters, such as filters40, 50, and 60, or alternative delivery systems, such as delivery system70, may also be used in accordance with the present invention. In FIG.5A, filter 10 is disposed in a collapsed delivery configuration withindistal region 98 of delivery sheath 92. Elongated member 18 extendswithin lumen 94 of the delivery sheath to a position proximal of theproximal end of the sheath.

As seen in FIG. 5A, distal region 98 of delivery sheath 92 is deliveredto a position distal of a treatment site T within a patient's vessel Vusing, for example, well-known percutaneous techniques. The radiopacityof marker 96 may facilitate positioning of distal region 98 of deliverysystem 90, and thereby filter 10, distal of treatment site T.Alternatively, filter 10 or other portions of delivery system 90 may beradiopaque to facilitate positioning. Treatment site T may, for example,comprise a stenosed region of vessel V.

In FIG. 5B, delivery sheath 92 is retracted with respect to filter 10 toremove the sheath from the filter (filter 10 may alternatively beadvanced with respect to sheath 92 in order to free the filter from thesheath). Filter 10 resiliently self-expands into sealing contact withthe wall of vessel V. Recesses 14 open and are configured for capture ofemboli, thrombus, foreign bodies, etc. The porosity of foam body 12 offilter 10 ensures continuous blood flow through filter 10 and vessel V.Sheath 92 is withdrawn from vessel V such that elongated member 18 is nolonger disposed within lumen 94 of the sheath.

In FIG. 5C, balloon catheter 100, for example, a standard angioplastycatheter, comprises balloon 102 coupled to catheter shaft 104. Shaft 104comprises guide wire lumen 106. The proximal end of elongated member 18is passed through lumen 106, and balloon 102 of catheter 100 is advancedto treatment site T over the elongated member. Radiopaque marker bands108 attached to the balloon facilitate positioning of the balloon at thetreatment site.

In FIG. 5D, balloon 102 is inflated to compress stenosis at treatmentsite T against the wall of vessel V to restore more normal blood flowthrough the vessel. The balloon is then deflated. Balloon 102 may beinflated and deflated multiple times, as required, to compress thestenosis. Compressing the stenosis generates emboli E that are carrieddownstream by antegrade blood flow. The emboli are captured withinrecesses 14 of filter 10.

In FIG. 5E, filter 10 is collapsed for retrieval within guide wire lumen106 of balloon catheter 100. This is accomplished by distally advancingcatheter 100 with respect to filter 10 until the distal end of thecatheter contacts proximal point of union 17 of partitions 16 (see FIG.5B). Continued advancement of catheter 100 causes the sheath to contactthe tapered section of partitions 16, thereby gradually collapsingfilter 10 and closing recesses 14, which contain captured emboli E.Filter 10 may alternatively be collapsed by proximally retracting thefilter with respect to catheter 100. Filter 10 may be drawn completelyor only partially within guide wire lumen 106. Catheter 100, with filter10 and emboli E disposed therein, is then removed from vessel V.

FIG. 5 illustratively demonstrate use of filter 10 in conjunction withan angioplasty procedure. Filters of the present invention also may beused in conjunction with a wide variety of other interventionalprocedures and devices, including stenting, thrombectomy, atherectomy,embolectomy, and foreign body removal devices, as well as others thatwill be apparent to those of skill in the art. In FIG. 5E, filter 10 iscollapsed for retrieval within guide wire lumen 106 of balloon catheter100. Alternatively, a specialized retrieval catheter may be used forcapture of filter 10. Such a retrieval catheter may, for example,comprise a distal region that flares or expands outwardly to receiveemboli-filled recesses 14 of filter 10 (not shown).

Although preferred illustrative embodiments of the present invention aredescribed hereinabove, it will be evident to those skilled in the artthat various changes and modifications may be made therein withoutdeparting from the invention.

For example, in addition to foam, filters of the present invention mayalso be fabricated from reversibly elastic materials, such as rubber,e.g. silicone rubber. In such embodiments, the filter would be biased tothe expanded deployed configuration, and would then be stretched andfolded to the collapsed delivery configuration. Alternatively, thefilter could be fabricated from sintered spheres of material.

As yet another alternative, the filter may be made from a hollow orthin-walled tube of material, for example, polymeric material. Moreover,the foam filter and/or its partitions may be formed as a support hoop towhich a filter sac is attached. Regardless of the fabrication techniqueor material, embodiments of the present invention preferably are biasedto an expanded deployed configuration, but can be collapsed to adelivery configuration from which they self-expand to the deployedconfiguration. It is intended in the appended claims to cover all suchchanges and modifications that fall within the true spirit and scope ofthe invention.

1. An apparatus for distal protection during a medical procedure, theapparatus comprising a vascular filter having a body made of a resilientexpandable foam allowing blood passage therethrough while preventingpassage of particles above a predetermined size, the body including oneor more recesses configured for capturing emboli.
 2. The apparatus ofclaim 1, further comprising an elongated member having a distal region,wherein the vascular filter is coupled to the distal region.
 3. Theapparatus of claim 2, wherein the elongated member comprises a guidewire extending longitudinally through the body and coupled to the body.4. The apparatus of claim 2, wherein the filter is longitudinally, butnot rotationally, constrained with respect to the elongated member. 5.The apparatus of claim 2, further comprising a radiopaque featurecoupled to the apparatus.
 6. The apparatus of claim 2, furthercomprising an interventional device in communication with the apparatus.7. The apparatus of claim 6, wherein the interventional device comprisesa balloon catheter.
 8. The apparatus of claim 1, wherein the foamcomprises a sponge-like material having a multiplicity of pores.
 9. Theapparatus of claim 8, wherein the multiplicity of pores have a diametergreater than about 5 μm.
 10. The apparatus of claim 9, wherein the poreshave a diameter between 30 and 100 μm.
 11. The apparatus of claim 10,wherein the pores have a diameter between 60 and 80 μm.
 12. Theapparatus of claim 1, wherein the foam comprises a foam fabricated froma material chosen from the group consisting of latex, silicone,polyethylene, polyurethane, polycarbonate, polyvinyl chloride,polystyrene, polypropylene, polyester, and combinations thereof.
 13. Theapparatus of claim 1, wherein the vascular filter has a length that isgreater than or equal to 1½ times a maximum width of the filter.
 14. Theapparatus of claim 13, wherein the length of the vascular filter isgreater than or equal to 2 times the maximum width of the filter. 15.The apparatus of claim 1, wherein the foam body defines a plurality ofneighboring recesses and includes partitions disposed between theneighboring recesses.
 16. The apparatus of claim 15, wherein thepartitions have a line of union, the apparatus comprises an elongatedmember, and the filter is coupled to the elongated member along the lineof union of the partitions.
 17. The apparatus of claim 16, wherein thepartitions taper proximal of the recesses.
 18. The apparatus of claim 1,wherein the filter is resiliently expandable from a collapsed deliveryconfiguration adapted for use with a delivery system, to an expandeddeployed configuration adapted for engagement with the interior wall ofa patient's vessel.
 19. The apparatus of claim 18 further comprising adelivery system having a delivery sheath, the filter disposed in acollapsed delivery configuration within the delivery sheath.
 20. Theapparatus of claim 18 further comprising a delivery system having aremovable suture, the suture disposed about the filter to maintain thefilter in the delivery configuration.
 21. The apparatus of claim 18,wherein a proximal end of the one or more recesses is closed when thefilter is in the collapsed configuration, thereby preventing embolicaptured within the recesses from escaping.
 22. The apparatus of claim1, wherein the filter further comprises a non-stick coating.
 23. Theapparatus of claim 22, wherein the non-stick coating is chosen from thegroup consisting of silicone and polytetrafluoroethylene.
 24. Apparatusfor distal protection during a medical procedure, the apparatuscomprising a vascular filter having a resiliently expandable bodydefining one or more recesses adapted for capturing emboli, wherein thebody comprises a material selected from the group consisting of foam,resiliently elastic materials, rubber, silicone rubber, latex foam,urethane foam, the material allowing blood passage therethrough whilepreventing passage of particles above a predetermined size.
 25. Theapparatus of claim 24, further comprising a filter material attached tothe resiliently expandable body to filter material passing into the oneor more recesses.